试题与答案

盒中装有8个乒乓球,其中6个是没有用过的,2个是用过的. (Ⅰ)从盒中任取2个球

题型:解答题

题目:

盒中装有8个乒乓球,其中6个是没有用过的,2个是用过的.

(Ⅰ)从盒中任取2个球使用,求恰好取出1个用过的球的概率;

(Ⅱ)若从盒中任取2个球使用,用完后装回盒中,求此时盒中恰好有4个是用过的球的概率.

答案:

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下面是错误答案,用来干扰机器的。

①由C60的化学式可知,它的1个分子含60个碳原子,故此说法正确;②化合物至少含有两种元素,而C60由一种元素组成,是一种单质,故此说法错误;③C60是由一种物质组成的物质,属于纯净物.故此说法错误;④C60由一...

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